If radioactive waste emits heat, why can’t we use it to produce energy?
In: 132
We can, but not enough to justify the cost. We can even convert the alpha/beta radiation into electricity directly, but the conversion efficiency is extremely poor so you’d need a high activity (dangerous) source that likely won’t be around for very long (short half life).
Someone from a nuclear waste disposal organisation I visited was asked the question “what would happen if you put a spent fuel cask in your basement”. She said, “you won’t have to pay for heating for the next few decades, but in return the [country’s nuclear regulator] and police will be paying regular visits to your house to check that nothing has gone missing and everything is still stored properly”.
So spent fuel is pretty efficient as a space heater – but you can’t just give the stuff out for safety and proliferation reasons.
TLDR: you can, it’s just not economical.
The vast majority of nuclear waste is not nearly as radioactive as people believe. The amount of High Level Waste (HLW) ever produced could fit in an area the size of a football field (pitch). There is some research around recycling HLW and using in alternative reactor designs, but it is still in the early stages.
“Most nuclear waste produced is hazardous, due to its radioactivity, for only a few tens of years and is routinely disposed of in near-surface disposal facilities (see above). Only a small volume of nuclear waste (~3% of the total) is long-lived and highly radioactive and requires isolation from the environment for many thousands of years.”
https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-wastes/radioactive-wastes-myths-and-realities.aspx
We do. That’s essentially how nuclear power plants work. Nuclear power plants use the heat from nuclear reactions to boil water. The steam spins a turbine that generates electricity.
We can and do. That’s how the radioisotope thermoelectric generators in some spacecraft work. There’s practical problems that mean other energy generation methods are usually better, but it certainly works.
We do. Radioisotope thermoelectric generator
are used in some spacecraft to generate electricity. The decay heat is converted to electricity though thermocouples. The problem is that radioactive decay can either be intense and fast or weak and slow.
For things like spacecraft that must operate for decades, you need the weak and slow kind of decay. This means you can’t generate a large amount of electricity but it does last a long time.
For commercial electricity generation, would you want to be the one that changes out the intensely radioactive source every day? It’s just impractical.
You could, and we kinda do. We use [RTGs](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator) in spacecraft and other more niche applications. Containment and contamination are always a concern, so you don’t see much of this type of tech in consumer applications besides some old 1st-gen pacemakers I think. I don’t know if the plutonium in those is actually from power plants however, so I’m not sure if RTG fuel is technically “waste” material.
We actually do reuse “waste” it can be refined and it is refined …… just not here in the USA.
https://www.energy.gov/ne/articles/5-fast-facts-about-spent-nuclear-fuel#:~:text=That’s%20right!,%2C%20such%20as%20France%2C%20do.
https://whatisnuclear.com/recycling.html
https://www.pnnl.gov/news-media/recycling-gives-new-purpose-spent-nuclear-fuel
Annnnd why we suck …. at almost everything…
https://www.google.com/amp/s/www.forbes.com/sites/realspin/2014/10/01/why-doesnt-u-s-recycle-nuclear-fuel/amp/
We could.
To some degree this is done, with a closed loop fuel cycle in some countries.
Other radioactive wastes could also be used to produce energy but it gets much more complicated beyond returning unused fuel into new fuel.
According to this Stanford physics student calculation
http://large.stanford.edu/courses/2012/ph241/tilghman1/
Using spent fuel natural radioactive decay as energy source (by pre-heating water for example) provides only a bonus of 0.067% of energy.
That seems to be too low for the nuclear power plant to change their design.
Right now, spent fuel are cooled in cooling pools in which all the heat is wasted by transferring it to cold water so that the pool remain cool and doesn’t produce any steam that could cause an explosion. It makes that the cooling pool doesn’t need to be as blinded as the reactor which is usually at moderately high temperature and pressure.
Spent fuel can be reused though by recycling their uranium and plutonium. Most of it is still usable after a cycle pass through. It’s the amount of fission product that stops the reaction, not the lack of fissile material. This is done in most countries other than the US.
Also, in the future, non-fissile actinides could be extracted and used in a fast neutron reactor, which will increase the amount of energy recoverable by more than 100 (mostly because the main component is U238 which is usable in a fast neutron reactor). It’s not economic to do so right now because uranium is extremely cheap for a given amount of energy and developing new types of reactors that are more efficient but still safe is very expensive.
The short answer: we *can,* but doing so is *hugely* inefficient (you’d need *a lot* of waste to generate a practical amount of heat), and cleaning up radioactive waste is *expensive*.
The cost of cleaning up the US’ Cold War-era nuclear waste was estimated by the General Accounting Office (GAO) a few years ago to be ~$377 billion, and that cost had jumped by $100 billion in a single year.
https://www.popularmechanics.com/military/weapons/a26145608/nuclear-waste-cleanup-cost-377-billion/
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